This invention relates to a device for the granulation of plastic material and particularly to the granulation of plastic scrap incident in the formation of injected molded plastic parts. More particularly, the invention is directed to a unique feed device wherein plastic scrap may be fed to the granulation chamber of the granulator in an even and consistent fashion and in such a manner as to minimize granulate fly-back through the feed device from the granulation chamber.
Devices of this general nature are known, and one particularly desirable commercial device incorporating such features is the 24T Auger Granulator produced and marketed by Cumberland Engineering Company, P. O. Box 6065, Providence, Rhode Island 02940. Such device includes a granulator adapted for dispostion essentially within the confines of an injection molding machine in the drop out area thereof. As such, plastic scrap, i.e., sprues and runners, fall directly by gravity into a pair of paddle rolls which act as a combination feed and metering means for the granulator whereby scrap is fed to the granulation chamber. Thereafter, the granulated scrap moves into a secondary chamber beneath the granulation chamber and in which an auger serves to continually move the granulate to that end of the granulator disposed generally at the entrance side of the injection molding machine drop out area. It has been found that this and other machines which utilize paddle rolls, wheels, or some similar arrangement in which to provide feed of material to another operative process are susceptible to jamming should material parts of a widely differing size be fed thereto. Such jamming, or at least interference of the normal functioning of the feed rolls because of the attempted acceptance of larger than normal material parts, may also force the paddle rolls out of synchronous movement. It, accordingly, would be useful to avoid these drawbacks and yet still be able to utilize the desirable features of paddle roll-type feeds as above discussed.
It is accordingly the primary object of the present invention to provide an improved feed means construction which enables parts of various sizes to be easily accepted without danger of either jamming or forcing opposed paddle roll components thereof out of synchronous movement with each other.
A further object of the present invention is the provision of the means by which one of the paddle roll components of the feed means may be temporarily laterally displaced with respect to the other of such paddle roll components to accomodate passage of a wide size variance of parts.
A still further object of the present invention is the provision of a unique drive means whereby the shafts of such paddle roll components are driven from one end thereof in such a manner so as to accomplish such synchronous movement yet still afford the flexible lateral movement of one shaft with respect to the other.
These and other objects of the present invention are accomplished by a granulation device having a housing in part definining a generally enclosed chamber, an elongated rotor mounted for rotation about an elongated axis within said chamber, cutting means provided on said rotor for cooperative cutting relationship with bed knife means mounted for projection into said chamber as said rotor is driven, elongated feed means positioned above and generally aligned with said rotor and at least partially enclosing said chamber at the upper end thereof and removal means positioned below said chamber for removing granulated scrap from said granulator, said feed means including a pair of elongated paddle rolls each having spaced blades radially extending from a central shaft, said blades adapted to interdigitate with each other as said shafts rotate in opposite directions towards each other so as to feed material into said chamber, said shafts supported by said housing and normally disposed parallel to each other within a generally laterally disposed plane disposed above said rotor with a first of said shafts fixed in position relative to said housing and the second shaft slidably supported in said housing for movement of any portion of said second shaft along the extent thereof towards and away from said first shaft within said lateral plane so as to accomplish increased spacing between said paddles at any location therealong including locations which will skew said second shaft with respect to said first shaft so as to afford the passage of oversized material therebetween, and drive means for driving said shafts in rotational synchronism at all times despite the relative lateral movement which may take place between said shafts.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.